Preformed part made of plastics with integrally formed rubber elastic parts

Abstract

A preformed part made of plastics material, especially a sheet-like plastics part made by injection molding is formed to be integral with elastic portions. The elastic portions serve as seals, as for feed-through holes in the plastics part. A ring-shaped circular closed protruding edge or ring-shaped rib, formed integrally with the plastics part around the regions to be coated with rubber, limit the region where elastic material is deposited to integrate with the plastics material. An annular region around rib has a radial span around the recesses, bore holes or edges into which the rubber material is injected, and enables insertion of the elastic material despite the presence of differential thermal expansion between the plastic part and a metal forming tool to shape the elastic material.

We claim: 
     
       1. In a part made of plastic, said part including a section having one of an edge or a hole coated with an elastic material for effective sealing thereat, said elastic material being applied to said section with a tool having a feed channel for feeding said elastic material, the improvement comprising: a protruding raised rib extending around said edge or hole, said rib being spaced from said edge or hole by a predetermined distance determined by the difference between the linear thermal expansion coefficient of said plastic and the material of the tool having said elastic material feed channel, said rib confining said elastic material to a zone defined by said raised rib and said edge or hole.   
     
     
       2. The part according to claim 1, wherein the side of said rib facing said edge or hole is covered by said elastic material. 
     
     
       3. The part according to claim 1, wherein said tool is made of steel. 
     
     
       4. A part according to claim 1, wherein: said elastic material is applied to contact a portion of a surface of said raised rib defining said zone.   
     
     
       5. A part according to claim 4, wherein: said elastic material and said plastics material remain in contact following application of the former to the latter.   
     
     
       6. A part according to claim 5, wherein: said elastic material comprises rubber material vulcanized in place following application confined by said raised rib.   
     
     
       7. A part according to claim 4, wherein: said predetermined distance is at least equal to the width of said raised rib.   
     
     
       8. A part according to claim 4, wherein: said elastic material comprises rubber material vulcanized in place following application confined by said raised rib.   
     
     
       9. A part according to claim 1, wherein: said elastic material and said plastics material remain in contact following application of the former to the latter.   
     
     
       10. A part according to claim 9, wherein: said elastic material comprises rubber material vulcanized in place following application confined by said raised rib.   
     
     
       11. A part according to claim 9, wherein: said predetermined distance is at least equal to the width of said raised rib.   
     
     
       12. A part according to claim 1, wherein: said predetermined distance is at least equal to the width of said raised rib.   
     
     
       13. A part according to claim 12, wherein: said elastic material comprises rubber material vulcanized in place following application confined by said raised rib.   
     
     
       14. A part according to claim 1, wherein: said elastic material comprises rubber material vulcanized in place following application confined by said raised rib.   
     
     
       15. A part according to claim 1, said section including one of a hole, bore and through-hole, and wherein said zone is within a region defined and substantially surrounded by the rib.